Semiconductor device including isolation regions

ABSTRACT

A semiconductor device including a device isolation region is provided. The semiconductor device includes first active regions disposed on a substrate, and an isolation region between the active regions. The isolation region includes a first portion formed of a first insulating material, and a second portion formed of a second insulating material, having different characteristics from those of the first insulating material. The first portion is closer to the first active regions than the second portion. The second portion has a bottom surface having a height different from that of a bottom surface of the first portion.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. patent application Ser. No.15/933,827, filed Mar. 23, 2018, which itself claims benefit of priorityunder 35 U.S.C § 119 to Korean Patent Application No. 10-2017-0123503filed on Sep. 25, 2017 in the Korean Intellectual Property Office, thedisclosures of both of which are hereby incorporated in their entiretiesby reference.

FIELD OF THE INVENTION

The present inventive concept relates to a semiconductor device, andmore particularly, to semiconductor devices including isolation regions,and methods of forming the same.

BACKGROUND

In general, active regions of semiconductor devices are defined byshallow trench isolation (STI). As semiconductor devices have beenhighly integrated, widths of active regions have gradually been reduced.With such a reduction in active regions, the occurrence of defects inactive regions is increasing.

SUMMARY

Some embodiments of the present inventive concept provide asemiconductor device including an isolation region defining an activeregion.

Some embodiments of the present inventive concept provide asemiconductor device including isolation regions formed of materialshaving different thermal degeneration characteristics.

Some embodiments of the present inventive concept provide methods offorming the semiconductor device.

According to some embodiments of the present inventive concept, asemiconductor device includes first active regions having first sidesarranged in a first direction and second sides arranged in a seconddirection, perpendicular to the first direction; second active regionshaving third sides arranged in the first direction and fourth sidesarranged in the second direction; a first isolation region adjacent thefirst and second sides of one of the first active regions; a secondisolation region adjacent the third sides of one of the second activeregions; and a third isolation region adjacent the fourth sides of oneof the second active regions. The first active regions are spaced apartfrom each other by a first distance in the first direction, the secondactive regions are spaced apart from each other by a second distance,shorter than the first distance, in the first direction, the firstisolation region and the second isolation region each include a firstinsulating material, and the first isolation region further includes asecond insulating material.

According to some embodiments of the present inventive concept, asemiconductor device includes first active regions on a substrate;second active regions on the substrate; a first isolation region betweenthe first active regions; and a second isolation region between thesecond active regions. The first isolation region and the secondisolation region each include a first insulating material, the firstisolation region further includes a second insulating material, thefirst isolation region includes a first portion formed of the firstinsulating material and a second portion formed of the second insulatingmaterial, the first portion is closer than the second portion to one ofthe first active regions, and the second insulating material is amaterial different from the first insulating material.

According to some embodiments of the present inventive concept, asemiconductor device includes active regions disposed on a substrate;and an isolation region between the active regions. The isolation regionincludes a first portion formed of a first insulating material, and asecond portion formed of a second insulating material havingcharacteristics different from those of the first insulating material,the first portion is closer than the second portion to one of the activeregions, and a bottom surface the second portion has a first heightdifferent from a second height of a bottom surface of the first portion.

BRIEF DESCRIPTION OF DRAWINGS

The above and other aspects, features, and advantages of the presentdisclosure will be more clearly understood from the following detaileddescription, taken in conjunction with the accompanying drawings, inwhich:

FIGS. 1A and 1B are plan views of an example of a semiconductor device,according to some embodiments of the present inventive concept;

FIGS. 2A and 2B are cross-sectional views of an example of asemiconductor device, according to some embodiments of the presentinventive concept;

FIG. 3 is a cross-sectional view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIG. 4 is a cross-sectional view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIG. 5 is a cross-sectional view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIG. 6 is a cross-sectional view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIG. 7 is a cross-sectional view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIG. 8 is a cross-sectional view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIG. 9A is a partially enlarged view of an example of a semiconductordevice, according to some embodiments of the present inventive concept;

FIG. 9B is a partially enlarged view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIG. 9C is a partially enlarged view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIGS. 9D and 9E are partially enlarged views of a modified example ofthe semiconductor device, according to some embodiments of the presentinventive concept;

FIG. 10 is a plan view of a modified example of the semiconductordevice, according to some embodiments of the present inventive concept;

FIG. 11A is a cross-sectional view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIG. 11B is a cross-sectional view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIG. 11C is a cross-sectional view of a modified example of thesemiconductor device, according to some embodiments of the presentinventive concept;

FIGS. 12 to 23 are views of an example of a method of forming asemiconductor device, according to some embodiments of the presentinventive concept;

FIGS. 24A to 28 are views of a modified example of the method of forminga semiconductor device, according to some embodiments of the presentinventive concept;

FIGS. 29A to 32 are views of a modified example of the method of forminga semiconductor device, according to some embodiments of the presentinventive concept; and

FIGS. 33 to 37 are views of a modified example of the method of forminga semiconductor device, according to some embodiments of the presentinventive concept.

DETAILED DESCRIPTION

It is noted that aspects of the inventive concept described with respectto one embodiment, may be incorporated in a different embodimentalthough not specifically described relative thereto. That is, allembodiments and/or features of any embodiment can be combined in any wayand/or combination. These and other objects and/or aspects of thepresent inventive concept are explained in detail in the specificationset forth below.

An example of a semiconductor device according to some embodiments willbe described with reference to FIGS. 1A, 1B, 2A and 2B. FIGS. 1A and 1Bare plan views of a semiconductor device according to an exampleembodiment. FIG. 2A illustrates cross-sectional views of regions takenon line I-I′ and line II-II′ of FIGS. 1A and 1B, and 2B illustratescross-sectional views of regions taken on line and line IV-IV′ of FIGS.1A and 1B.

Referring to FIGS. 1A, 1B, 2A and 2B, a substrate 3 having a firstregion A1 and a second region A2 may be provided. The substrate 3 may bea semiconductor substrate that may be formed of a semiconductor materialsuch as silicon or the like. The first region A1 may be a first circuitregion, and the second region A2 may be a second circuit region. Forexample, the first region A1 may be a logic circuit region, and thesecond region A2 may be a static random access memory (SRAM) circuitregion.

In the substrate 3, isolation regions may be disposed to define activeregions.

The active regions may include first active regions 12 disposed on thefirst region A1, and active base regions 132 and second active regions112, disposed on the second region A2.

In the first region A1, the first active regions 12 may extend from thesubstrate 3 in a vertical direction Z. The vertical direction Z may be adirection perpendicular to an upper surface of the substrate 3.

The first active regions 12 may include first sides S1, arranged in afirst direction X, and second sides S2, arranged in a second directionY, perpendicular to the first direction X. The first active regions 12may be spaced apart from each other with a first distance L1therebetween, in the first direction X.

In the second region A2, the active base regions 132 may extend from thesubstrate 3 in the vertical direction Z.

The second active regions 112 may extend from the active base regions132 in the vertical direction Z.

The second active regions 112 may include third sides S3 arranged in thefirst direction X, and fourth sides S4 arranged in the second directionY.

The second active regions 112 may be spaced apart from each other by asecond distance L2, shorter than the first distance L1, in the firstdirection X. Thus, in the first direction X, the second distance L2between the second active regions 112 adjacent to each other may beshorter than the first distance L1 between the first active regions 12,adjacent to each other.

A distance between the active base regions 132 may be greater than thefirst distance L1 between the first active regions 12, adjacent to eachother.

The fourth sides S4 of the second active regions 112 may be self-alignedwith a side of the active base region 132. The third sides S3 of thesecond active regions 112 may overlap the active base region 132, andmay not be self-aligned with a side of the active base region 132.

The isolation regions may include a first isolation region 27 disposedin the first region A1 of the substrate 3, and a second isolation region115 and a third isolation region 136, disposed in the second region A2of the substrate 3.

The first isolation region 27 may define the first active regions 12.The first isolation region 27 may be disposed between the first activeregions 12. The first isolation region 27 may face the first sides S1and the second sides S2 of the first active regions 12.

The first isolation region 27 may include a first portion 15 and asecond portion 24. In the first isolation region 27, the first portion15 may be formed to be closer to the first active regions 12 than thesecond portion 24 is. The second isolation region 115 may face the thirdsides S3 of the second active regions 112. The third isolation region136 may extend upwardly while defining the active base region 132.

The third isolation region 136 may extend upwardly while surrounding aside of the active base region 132, to face the fourth sides S4 of thesecond active regions 112. The third sides S3 of the second activeregions 112 may face the second isolation regions 115, and the fourthsides S4 of the second active regions 112 may face the third isolationregion 136. Thus, the second active regions 112 may be defined by thesecond and third isolation regions 115 and 136. The third isolationregion 136 may surround the second active regions 112 and the secondisolation region 115 when viewed in plan view.

In some embodiments, the first isolation region 27 and the secondisolation region 115 may commonly include a first insulating material.For example, the second isolation region 115 and the first portion 15 ofthe first isolation region 27 may be formed of the first insulatingmaterial. The first isolation region 27 may further include a secondinsulating material, as compared to the second isolation region 115. Forexample, the second portion 24 of the first isolation region 27 may beformed of the second insulating material, different from the firstinsulating material.

In some embodiments, the first insulating material may be a materialhaving etch selectivity with respect to the second insulating material.The first insulating material may be a material having an etching ratehigher than that of the second insulating material. The secondinsulating material may be a material harder than the first insulatingmaterial. For example, the first insulating material may be aflowable-CVD oxide or a flowable oxide, and the second insulatingmaterial may be a material formed using an atomic layer deposition (ALD)method.

In some embodiments, the first and second insulating materials may havedifferent densities, while being oxide-based materials. For example, thefirst insulating material may be a flowable-CVD oxide or a flowableoxide, and the second insulating material may be silicon oxide formed byan ALD method.

In some embodiments, the second insulating material may be a materialharder or denser than the first insulating material, or may be amaterial having an etching rate of an oxide etchant lower than anetching rate of the oxide etchant of the first insulating material.

In some embodiments, the first insulating material may be an oxide-basedmaterial, and the second insulating material may be a nitride-basedmaterial, for example, silicon nitride or silicon oxynitride (SiON).

The third isolation region 136 may include a material different from thefirst insulating material. For example, the third isolation region 136may include a third insulating material, different from the firstinsulating material. The third insulating material may have etchselectivity with respect to the first insulating material. For example,the first insulating material may be a material having a higher etchingrate with respect to an oxide etchant than an etching rate of the thirdinsulating material. The third insulating material may be a hardermaterial than the first insulating material. For example, the firstinsulating material may be a flowable-CVD oxide or a flowable oxide, andthe third insulating material may be an a high density plasma (HDP)oxide, a tetraethyl orthosilicate (TEOS) oxide, a undoped silicon glass(USG) oxide, or the like.

In some embodiments, the third insulating material may be a materialdifferent from the first and second insulating materials. For example,the first insulating material may be a flowable-CVD oxide or a flowableoxide, the second insulating material may be a silicon oxide, a siliconnitride or a silicon oxynitride formed using an ALD method, and thethird insulating material may be HDP oxide, TEOS oxide, USG oxide, orthe like.

In the first region A1, first gate structures 240 may be disposed toextend in the first direction X and have portions overlapping the firstactive regions 12, and first source/drain regions 210 may be disposed tobe connected to the first active regions 12 located adjacent to thefirst gate structures 240.

In the second region A2, second gate structures 340 may be disposed toextend in the first direction X and have portions overlapping the secondactive regions 112, and second source/drain regions 310 may be disposedto be connected to the second active regions 112 located adjacent to thesecond gate structures 340.

Each of the first gate structures 240 may include a first gatedielectric 223, a first gate electrode 226, a first gate capping layer229 and a first gate spacer 232.

The first gate capping layer 229 may be disposed on the first gateelectrode 226. The first gate spacer 232 may be disposed on sides of thefirst gate electrode 226 and the first gate capping layer 229. The firstgate dielectric 223 may be disposed between the first gate electrode 226and the first active regions 12, and may extend between the first gateelectrode 226 and the first gate spacer 232.

Each of the second gate structures 340 may include a second gatedielectric 323, a second gate electrode 326, a second gate capping layer329, and a second gate spacer 332. The second gate capping layer 329 maybe disposed on the second gate electrode 326. The second gate spacer 332may be disposed on sides of the second gate electrode 326 and the secondgate capping layer 329. The second gate dielectric 323 may be disposedbetween the second gate electrode 326 and the second active regions 112,and may extend between the second gate electrode 326 and the second gatespacer 332.

First contact plugs 260 may be disposed on the first source/drainregions 210, and second contact plugs 360 may be disposed on the secondsource/drain regions 310. Interlayer insulation layers 250 and 350 maybe disposed on the first and third isolation regions 27 and 136,respectively.

In an example, in the second source/drain regions 310, adjacent secondsource/drain regions 310 may be connected to each other. An empty space308 may be formed between the second source/drain regions 310 connectedto each other and the second isolation region 115. The empty space 308may comprise an air gap or other area that is void of material.

In some embodiments, the first isolation region 27 may include a firstportion 15 and a second portion 24, and the first portion 15 maysurround a side surface and a bottom surface of the second portion 24.However, the technical idea of the present inventive concept is notlimited thereto. Modifications of the first isolation region 27 will bedescribed with reference to FIGS. 3, 4, 5 and 6. FIGS. 3, 4, 5 and 6 arecross-sectional views of regions taken along lines I-I′ and II-II′ ofFIGS. 1A and 1B.

With reference to FIG. 3, the first isolation region 27 may include afirst portion 15 and a second portion 24. The second portion 24 may bemodified to penetrate through the first portion 15.

With reference to FIG. 4, the first isolation region 27 may include afirst portion 15 and a second portion 24, and the second portion 24 maypenetrate through the first portion 15 and may be modified to extendinto the substrate 3. The first portion 15 may have a downwardly convexbottom surface 15 b, and the second portion 24 may penetrate through thebottom surface 15 b of the first portion 15. The bottom surfaces 15 b ofregions of the first portion 15, separated by the second portion 24 andlocated on both sides of the second portion 24, may have a form loweredin a direction toward the second portion 24.

In some embodiments, the bottom surface 15 b of the first portion 15 anda bottom surface 24 b of the second portion 24 may form an obtuse angleθ1.

Referring to FIG. 5, the first isolation region 27 may include a firstportion 15 and a second portion 24, and a bottom surface of the secondportion 24 may be disposed on a level higher than that of a bottomsurface of the first portion 15. In an example, a bottom surface 15 b ofthe first portion 15 may be downwardly convex, and a bottom surface 24 bof the second portion 24 may be downwardly convex.

The first portion 15 located on both sides of the second portion 24 maybe downwardly convex. Thus, a protrusion P protruding from the substrate3 may be disposed between the bottom surface 15 b of the first portion15 and the bottom surface 24 b of the second portion 24.

In an example, the bottom surface 15 b of the first portion 15 and thebottom surface 24 b of the second portion 24 may form an acute angle θ2.

With reference to FIG. 6, the first isolation region 27 may include afirst portion 15 and a second portion 24, and the second portion 24 mayextend into the substrate 3 while penetrating through the first portion15. Bottom surfaces 15 b of regions of the first portion 15, separatedby the second portion 24 and located on both sides of the second portion24, may respectively be downwardly convex. In an example, the bottomsurface 15 b of the first portion 15 and the bottom surface 24 b of thesecond portion 24 may form an acute angle θ2.

Referring again to FIGS. 1A, 1B, 2A and 2B, the third isolation region136 may be formed of the third insulating material, but a materialthereof is not limited thereto. A modified example of the thirdisolation region 136 and a modified example of the first isolationregion 27 will be described with reference to FIGS. 7 and 8,respectively. FIGS. 7 and 8 are cross-sectional views of regions takenalong lines I-I′ and II-II′ of FIGS. 1A and 1B.

Referring to FIG. 7, the third isolation region 136 may be modified toinclude a first portion 124 and a second portion 134. In the modifiedthird isolation region 136 as described above, the first portion 124 ofthe third isolation region 136 may surround a side surface and a bottomsurface of the second portion 134 of the third isolation region 136.

The first isolation region 27 may include a first portion 15 and asecond portion 24, and the second portion 24 of the first isolationregion 27 may penetrate through the first portion 15 of the firstisolation region 27, and may be modified to extend into the substrate 3.A bottom surface 24 b of the second portion 24 of the first isolationregion 27 and a bottom surface 15 b of the first portion 15 of the firstisolation region 27 may form an obtuse angle θ1.

The first portion 15 of the first isolation region 27 and a secondisolation region 115 may be formed of the first insulating material, thesecond portion 24 of the first isolation region 27 and the first portion124 of the third isolation region 136 may be formed of the same secondinsulating material, and the second portion 134 of the third isolationregion 136 may be formed of the third insulating material.

Referring to FIG. 8, the third isolation region 136 may include a firstportion 124 and a second portion 134, identical to those described inFIG. 7.

The first isolation region 27 may include a first portion 15 and asecond portion 24. The first portion 15 of the first isolation region 27may have a downwardly convex bottom surface 15 b, and the second portion24 of the first isolation region 27 may penetrate through the firstportion 15 of the first isolation region 27 and extend into thesubstrate 3.

A bottom surface 24 b of the second portion 24 of the first isolationregion 27 and a bottom surface 15 b of the first portion 15 of the firstisolation region 27 may form an acute angle θ2.

Next, some embodiments of the first isolation region 27 according to anexample embodiment will be described with reference to FIGS. 9A, 9B, and9C, respectively. FIGS. 9A, 9B and 9C are partially enlarged views ofportion B of FIG. 2A.

Examples of the first isolation region 27 will be described withreference to FIGS. 9A, 9B and 9C, together with the descriptions abovewith respect to FIGS. 1A to 8. Thus, the following descriptions withreference to FIGS. 9A, 9B and 9C can be understood in conjunction withthe contents and components described above with reference to FIGS. 1 to8, even without separate descriptions below.

Referring to FIG. 9A, the first isolation region 27 may include a firstportion 15 and a second portion 24, as described above. The firstportion 15 may be formed to be closer to a first active region 12 thanthe second portion 24 is.

The first isolation region 27 may have an upper surface disposed on alevel lower than that of an upper surface 12 s of the first activeregion 12. In an example, the upper surface of the first isolationregion 27 may include a first surface 15 s and a second surface 24 sdisposed on a level higher than that of the first surface 15 s. Thefirst surface 15 s of the upper surface of the first isolation region 27may be an upper surface of a portion of the first portion 15 close tothe second portion 24.

Referring to FIG. 9B, an insulating spacer 233 may be disposed betweenthe first isolation region 27 and the first source/drain region 210.Thus, the first isolation region 27 and the first source/drain region210 may be spaced apart by the insulating spacer 233.

In some embodiments, the insulating spacer 233 may be formed of the samematerial as the first and second gate spacers 232 and 332.

In some embodiments, the insulating spacer 233 may cover a portion 15 s1 of the upper surface of the first portion 15, and may not cover aremaining portion 15 s 2 of the upper surface of the first portion 15.

In some embodiments, the portion 15 s 1 of the upper surface of thefirst portion 15, covered by the insulating spacer 233, may be disposedon a level higher than that of the upper surface 24 s of the secondportion 24, and the remaining portion 15 s 2 of the upper surface of thefirst portion 15, not covered by the insulating spacer 233, may bedisposed on a level lower than that of the upper surface 24 s of thesecond portion 24.

Referring to FIG. 9C, an insulating spacer 233 may be disposed betweenthe first isolation region 27 and the first source/drain region 210, andthe insulating spacer 233 may cover an upper surface 15 s of the firstportion of the first isolation region 27. The upper surface 15 s of thefirst portion 15, covered by the first insulating spacer 233, may bedisposed on a level higher than that of an upper surface 24 s of thesecond portion 24.

Subsequently, a modified example of the semiconductor device accordingto some embodiments will be described with reference to FIGS. 9D and 9E.FIGS. 9D and 9E are partially enlarged views of portion B of FIG. 2A.Hereinafter, FIGS. 9D and 9E will be described in conjunction with thecontents and components described above with reference to FIGS. 1 to 9Cwithout any separate descriptions.

Referring to FIGS. 9D and 9E, a buffer oxide 13 may be formed betweenthe first isolation region 27 and first active regions 12 and/or betweenthe second isolation region 115 and second active regions 112. Thebuffer oxide 113 may be formed by a thermal oxidation process performedto prevent an etching damage on surfaces of the first and second activeregions 12 and 112, that may occur due to an etching process performedto form the first and second active regions 12 and 112. For example, thebuffer oxide 113 may be thermal oxide that may be formed in a thermaloxidation process.

Referring again to FIGS. 1A, 1B, 2A and 2B, in the first isolationregion 27 including the first portion 15 and the second portion 24, thesecond portion 24 may have a linear shape in which a plurality of secondportions are disposed to be spaced apart from each other, but the shapeof the second portion is not limited thereto. Modifications of the firstisolation region 27 will be described with reference to FIGS. 11A, 11Band 11C together with FIG. 10. FIGS. 11A, 11B and 11C arecross-sectional views of regions taken along lines IV-IV′ of FIGS. 1Aand 1B.

Referring to FIGS. 10 and 11A, the first isolation region 27 includingfirst and second portions 15 and 24 may further include a connectingportion 25 extending from one side of the second portion 24 in the firstdirection X to be connected to a neighboring second portion 24. Thus, inthe first isolation region 27, the connecting portion 25 may extend fromthe second portion 24 and may be formed of the same second insulatingmaterial as the second portion 24. The second portion 24 and theconnecting portion 25 may be integrally formed.

In an example, when the side and bottom surfaces of the second portion24 are surrounded by the first portion 15, as illustrated in FIG. 2A, aside surface and a bottom surface of the connecting portion 25 may besurrounded by the first portion 15.

In a modified example, when the second portion 24 penetrates through thefirst portion 15 as illustrated in FIG. 3, the connecting portion 25 mayalso penetrate through the first portion 15 as illustrated in FIG. 11B.

In another modification, in a similar case as illustrated in FIG. 4, inwhich the second portion 24 extends into the substrate 3 whilepenetrating through the first portion 15, the connecting portion 25 mayalso extend into the substrate 3 while penetrating through the firstportion 15 as illustrated in FIG. 11C.

Hereinafter, various methods in which the foregoing semiconductordevices may be formed will be described with reference to FIGS. 12 to37. FIGS. 12 to 23 are views of illustrative examples of a method offorming a semiconductor device according to some embodiments, FIGS. 24Ato 28 are views of a modified example of the method of forming asemiconductor device according to an example embodiment, FIGS. 29A to 32are views of a modified example of the method of forming a semiconductordevice according to some embodiments, and FIGS. 33 to 37 are views of amodified example of the method of forming a semiconductor deviceaccording to some embodiments.

First, referring to FIGS. 12 to 23, illustrative examples of a method offorming a semiconductor device according to example embodiments will bedescribed. In FIGS. 12 to 23, FIGS. 12, 14, FIGS. 16A and 20 are planviews of an example of a method of forming a semiconductor deviceaccording to some embodiments, and FIGS. 13, 15, 17, 18A, 19, 21A, 21B,22 and 23 are cross-sectional views of regions taken along lines I-I′and II-II′ of FIGS. 12, 14, 16A and 20. FIG. 16B is a plan view of amodified example of the method of forming a semiconductor deviceaccording to some embodiments, FIG. 18B is a cross-sectional view of amodified example of the method of forming a semiconductor deviceaccording to some embodiments, and FIG. 18C is a cross-sectional view ofa modified example of the method of forming a semiconductor deviceaccording to some embodiments.

First with reference to FIGS. 12 and 13, hard masks may be formed on asubstrate 3 having a first region A1 and a second region A2. The firstregion A1 may be a first circuit region, and the second region A2 may bea second circuit region. For example, the first region A1 may be a logiccircuit region, and the second region A2 may be an SRAM circuit region.The substrate 3 may be a semiconductor substrate that may be formed of asemiconductor material such as silicon or the like.

The hard masks may be formed of a material, such as silicon nitrideand/or silicon oxide, or the like. The hard masks may include first hardmasks 6 a formed on the first region A1, and second hard masks 106formed on the second region A2.

The first and second hard masks 6 a and 106 may be arranged to have aconstant interval therebetween in a first direction X. The first andsecond hard masks 6 a and 106 may have a linear shape extending in asecond direction Y, perpendicular to the first direction X.

Referring to FIGS. 14 and 15, portions of the first hard masks (see 6 aof FIG. 12) may be patterned and removed. Thus, first hard masks 6 bformed by patterning the portions of the first hard masks (6 a of FIG.12) may be provided.

An interval between the patterned first hard masks 6 b arranged in thefirst direction X may be greater than an interval between the secondhard masks 106 arranged in the first direction X.

The substrate 3 may be etched in an etching process in which the firstand second hard masks 6 b and 106 are used as etching masks, to formfirst and second trenches 9 and 109, while forming first and secondactive regions 12 and 112 remaining below the first and second hardmasks 6 b and 106.

Of the first and second trenches 9 and 109, the first trenches 9 may beformed on the first region A1, to define the first active regions 12,and the second trenches 109 may be formed on the second region A2, todefine the second active regions 112. The interval between the firstactive regions 12 arranged in the first direction X may be greater thanthe interval between the second active regions 112 arranged in the firstdirection X.

Referring to FIGS. 16A and 17, a first preliminary isolation region 15may be formed in the first trenches 9, and a second isolation region 115may be formed in the second trenches 109.

Forming the first preliminary isolation region 15 and the secondisolation region 115 may include forming a first insulating material ona substrate having the trenches 9 and 109, and planarizing the firstinsulating material until the first and second hard masks 6 b and 106are exposed. The first preliminary isolation region 15 and the secondisolation region 115 may be formed of the same first insulatingmaterial.

A first photoresist pattern 18 may be formed on the substrate having thefirst preliminary isolation region 15 and the second isolation region115.

The first photoresist pattern 18 may expose a portion of the firstregion A1, while covering the entirety of the second region A2. On thefirst region A1, the first photoresist pattern 18 may be formed to coverthe first hard masks 6 b while having a larger size than the first hardmasks 6 b. Thus, the first photoresist pattern 18 may cover the entiretyof the second region A2, and may cover the first hard masks 6 b of thefirst region A1 while exposing portions of the first preliminaryisolation regions 15 of the first region A1.

In some embodiments, in the case of the first photoresist pattern 18,portions thereof formed on the first region A1 may have linear shapesspaced apart from each other.

In a modified example, as illustrated in FIG. 16B, in the firstphotoresist pattern 18, a portion 18 thereof, formed on the first regionA1, may be modified to have partially cut linear shapes. The firstphotoresist pattern 18 modified as illustrated in FIG. 16B may be usedas a photoresist pattern for formation of the connecting portion 25described above with reference to FIGS. 10 and 11A.

Referring to FIG. 18A, the first preliminary isolation region 15 in thefirst region A1 may be partially etched by performing an etching processof using the first photoresist pattern 18 as an etching mask. Thus,grooves 21 a may be formed in the first preliminary isolation region 15in the first region A1. The grooves 21 a may be located on levels higherthan bottom surfaces of the first trenches 9.

In a modified example, as illustrated in FIG. 18B, an etching processusing the first photoresist pattern 18 as an etching mask may beperformed to form grooves 21 b penetrating through the first preliminaryisolation region 15 of the first region A1 and exposing the substrate 3.

In another modification, as illustrated in FIG. 18C, an etching processusing the first photoresist pattern 18 as an etching mask may beperformed to form grooves 21 c, penetrating through the firstpreliminary isolation region 15 of the first region A1 and extendinginto the substrate 3.

Hereinafter, the substrate having the grooves 21 a as illustrated inFIG. 18A will be described, rather than the substrate having the grooves21 b and 21 c as illustrated in FIGS. 18B and 18C. The substrate havingthe grooves 21 a as illustrated in FIG. 18A, to be described below, mayalso be replaced with the substrates having the grooves 21 b and 21 c asillustrated in FIGS. 18B and 18C. Thus, although descriptions below willbe centered on the substrate having the grooves 21 a described abovewith reference to FIG. 18A, the substrate may be replaced withsubstrates having the grooves 21 b and 21 c as illustrated in FIGS. 18Band 18C.

Referring to FIG. 19, after removing the first photoresist pattern 18, asecond insulating material may be deposited on the substrate having thegrooves 21 a, and the second insulating material may be planarized untilthe hard masks 6 b and 106 are exposed, thereby forming the firstisolation region 27.

In example embodiments, the first preliminary isolation region 15 may bereferred to as a first portion 15 of the first isolation region 27, andthe second insulating material filling the grooves 21 a may be referredto as a second portion 24 of the first isolation region 27.

Referring to FIGS. 20 and 21A, a second photoresist pattern 30 may beformed on a substrate having the first isolation region 27 and thesecond isolation region 115. The second photoresist pattern 30 may coverthe entirety of the first region A1 and/or cover a portion of the secondregion A2.

With reference to FIG. 21B, an etching process using the secondphotoresist pattern 30 as an etching mask may be performed to etch thesecond isolation region 115 and the second active regions 112 on thesecond region A2, thereby forming a third trench 133. The third trench133 may have a bottom surface deeper than bottoms of the first andsecond trenches 9 and 109. An active base region 132, defined by thethird trench 133, may be formed. The second active regions 112 mayremain on the active base region 132.

Referring to FIG. 22 together with FIG. 1A, after the second photoresistpattern 30 is removed, a third isolation region 136 may be formed tofill the third trench 133. The third isolation region 136 may be formedof a third insulating material.

Referring to FIG. 23, after the first and second hard masks 6 b and 106are removed, the first to third isolation regions 27, 115 and 136 may beetched back to expose upper regions of the first and second activeregions 12 and 122. Thus, the upper regions of the first and secondactive regions 12 and 112 may form exposed fins.

Referring again to FIGS. 1A, 1B, 2A and 2B, a transistor formationprocess may be performed with respect to a substrate having the firstand second active regions 12 and 112, and the first to third isolationregions 27, 115 and 136. In an example, the transistor formation processmay include forming a sacrificial gate structure overlapping the firstand second active regions 12 and 112, forming gate spacers on sides ofthe sacrificial gate structure, forming a recessed region by etching thefirst and second active regions 12 and 112 adjacent to the sacrificialgate structure, growing an epitaxial layer from the recessed region tobe doped to form source/drain regions, removing the sacrificial gatestructure, and forming a gate dielectric, a gate electrode, and a gatecapping pattern in a space from which the sacrificial gate structure hasbeen removed.

Thus, in the first region A1, first gate structures 240 extending in afirst direction X and having a portion overlapping the first activeregions 12, and first source/drain regions 210 connected to the firstactive regions 12 positioned adjacent to the first gate structures 240,may be formed. In the second region A2, second gate structures 340extending in the first direction X and having a portion overlapping thesecond active regions 112, and second source/drain regions 310 connectedto the second active regions 112 positioned adjacent to the second gatestructures 340, may be formed.

In some embodiments, the first source/drain regions 240 formed on thefirst region A1 may be spaced apart from each other.

In some embodiments, source/drain regions adjacent to each other, amongthe second source/drain regions 310 formed on the second region A2, maybe connected to each other. Thus, an empty space 308 may be formedbetween a lower portion of the second source/drain regions 310 connectedto each other, and the second isolation region 115.

Next, a modified example of the method of forming a semiconductor deviceaccording to some embodiments will be described with reference to FIGS.24A to 28. FIG. 24A is a plan view of a modified example of the methodof forming a semiconductor device according to some embodiments, andFIGS. 25 to 28 are cross-sectional views taken along line I-I′ and lineII-II′ of FIG. 24a . FIG. 24B is a plan view of another modification ofthe method of forming a semiconductor device according to an exampleembodiment.

Referring to FIGS. 24A and 25, a substrate formed up to the first andsecond trenches (see 9 and 109 of FIG. 15) described with reference toFIGS. 14 and 15 may be prepared. Subsequently, a first preliminaryisolation region 15 may be formed to fill the first trench 9, and asecond isolation region 115 may be formed to fill the second trench 109.The first preliminary isolation region 15 and the second isolationregion 115 may be formed of a first insulating material.

A photoresist pattern 318 may be formed on the substrate 3 on which thefirst preliminary isolation region 15 and the second isolation region115 have been formed.

In the first region A1, the photoresist pattern 318 may be formed tohave the same shape and size as those of the first photoresist pattern(see 18 of FIGS. 16A and 17) of the first region A1, described abovewith reference to FIGS. 16A and 17.

In the second region A2, the photoresist pattern 318 may be formed tohave the same shape and size as those of the second photoresist pattern(see FIGS. 20 and 21A) of the second region A2, described above withreference to FIGS. 20 and 21A.

In a modified example, as illustrated in FIG. 24B, the photoresistpattern 318 in the first region A1 may be formed to have the same shapeand size as those of the modified first photoresist pattern (see 18 ofFIG. 16B) of the first region A1, described above with reference to FIG.16B.

Referring to FIG. 26, an etching process using the photoresist pattern318 as an etching mask may be performed, to form grooves 21 penetratingthrough the first preliminary isolation region 15 in the first region A1and extending into the substrate 3, and to also form a third trench 133in the second region A2. The grooves 21 may have a shape and structuresimilar to those of the grooves (see 21 of FIG. 18C) described abovewith reference to FIG. 18C. The third trench 133 may have a shape andstructure similar to those of the third trench (see 133 of FIG. 21B)described above with reference to FIG. 21B.

Referring to FIG. 27, the photoresist pattern 318 may be removed. Then,a second insulating material layer 23 may be formed to fill the grooves21 and conformally cover an inner wall of the third trench 133.

Referring to FIG. 28, a third insulating material layer may be formed onthe substrate having the second insulating material layer 23, to fill aremaining portion of the third trench 133, and the third insulatingmaterial layer and the second insulating material layer (see 23 of FIG.27) may be planarized until the first and second hard masks 6 b and 106are exposed.

In the first region A1, the second insulating material layer (see 23 ofFIG. 27) may remain to be formed as a second portion 24 of the firstisolation region 27. The first preliminary isolation region 15 remainingin the first region A1 may be referred to as a first portion 15 of thefirst isolation region 27.

In the second region A2, the second insulating material layer 23 (seeFIG. 27) may remain to be formed as a first portion 124 of a thirdisolation region 136, and the third insulating material layer may remainto be formed as a second portion 134 of the third isolation region 136.

Then, after the process of etching back the first to third isolationregions 27, 115 and 136 as described above with reference to FIG. 23 isperformed, the transistor formation process may be performed.

Next, a modified example of the method of forming a semiconductor deviceaccording to some embodiments will be described with reference to FIGS.29A to 32. FIG. 29A is a plan view of a modified example of the methodof forming a semiconductor device according to some embodiments, andFIGS. 30, 31A and 32 are cross-sectional views of regions taken alonglines I-I′ and II-II′ of FIG. 29A. FIG. 29B is a plan view of anothermodification of the method of forming a semiconductor device accordingto some embodiments. FIG. 31B is a cross-sectional view of anothermodification of the method of forming a semiconductor device accordingto some embodiments.

Referring to FIGS. 29A and 30, a substrate 3 formed up to the same firstand second hard masks 6 a and 106 as those described above with respectto FIGS. 12 and 13 may be prepared.

An etching process using the first and second hard masks 6 a and 106 asetching masks may be performed to etch the substrate 3, to form firstpreliminary trenches 8 in the first region A1 and to form secondtrenches 109 in the second region A2.

First preliminary isolation regions 15 may be formed to fill the firstpreliminary trenches 8, and second isolation regions 115 may be formedto fill the second trenches 109.

The first preliminary isolation regions 15 may define first preliminaryactive regions 11, and the second isolation regions 115 may definesecond active regions 112.

A photoresist pattern 418 may be formed on the substrate having thefirst preliminary isolation regions 15 and the second isolation regions115.

The photoresist pattern 418 may expose a portion of the first region A1while covering the entirety of the second region A2. A portion of thefirst hard masks 6 a and a portion of the first preliminary isolationregions 15 may be exposed by the photoresist pattern 418.

In a modified example, the first hard masks 6 a may have a shape inwhich a portion thereof is patterned, as illustrated in FIG. 29B. Forexample, in the case of the first hard masks 6 a that may have linearshapes, arranged to have a constant interval therebetween in the firstdirection X and extending in the first direction X, a portion of thefirst hard masks 6 a may be patterned and removed in a second directionY perpendicular to the first direction X. A photoresist pattern 418 maybe formed on the first hard masks 6 a modified as described above, asillustrated in FIG. 29B. The photoresist pattern 418 in FIG. 29B may beformed to have the same shape and size as those of the first photoresistpattern (see 18 of FIG. 16A) in the first region A1 described above withreference to FIGS. 16A and 17.

Referring to FIG. 31A, an etching process using the photoresist pattern418 as an etching mask may be performed, to etch a portion of the firstpreliminary isolation regions 15, a portion of the first hard masks 6 a,and a portion of the first preliminary active regions 11, and thus formthe grooves 21.

The first preliminary active regions remaining after forming the grooves21 may be defined as first active regions 12. An interval between thefirst active regions 12 may be greater than an interval between thefirst preliminary active regions (see 11 of FIG. 30). The first hardmasks 6 b may remain on the first active regions 12.

In an example embodiment, bottom surfaces of the grooves 21 may bedisposed to be higher than bottom surfaces of the first preliminaryisolation regions 15, but the technical idea thereof is not limitedthereto. For example, as illustrated in FIG. 31B, the grooves 21 may bemodified, to extend into the substrate 3 and have bottom surfaces lowerthan bottom surfaces of the first preliminary isolation regions 15.

Referring to FIG. 32, after the photoresist pattern 418 is removed, asecond insulating material may be deposited on the substrate having thegrooves 21, in the same manner as described above with reference to FIG.19, and the second insulating material may be planarized until the firstand second hard masks 6 b and 106 are exposed, to form the firstisolation region 27. As illustrated in FIG. 19, the first preliminaryisolation region 15 may be referred to as a first portion 15 of thefirst isolation region 27, and the second insulating material fillingthe grooves 21 a may be referred to as a second portion 24 of the firstisolation region 27.

Then, the third isolation region 136, the same as that illustrated inFIG. 22, may be formed in the second region A2 by performing the sameprocess as described above with reference to FIGS. 20 to 22.

Subsequently, after the process of etching back the first to thirdisolation regions 27, 115 and 136 as described above with reference toFIG. 23 is performed, the transistor formation process may be performed.

Next, a modified example of the method of forming a semiconductor deviceaccording to some embodiments will be described with reference to FIGS.33 to 37. FIG. 33 is a plan view of a modified example of the method offorming a semiconductor device according to some embodiments, and FIGS.34 to 37 are cross-sectional views of regions taken along lines I-I′ andII-II′ of FIG. 33.

Referring to FIGS. 33 and 37, a substrate 3 formed up to the firstpreliminary isolation regions 15 defining the first preliminary activeregions 11, and the second isolation regions 115 defining the secondactive regions 112, identical to those described above with reference toFIGS. 29A and 30, may be prepared. The first hard masks 6 a may remainon the first preliminary active regions 11, and the second hard masks106 may remain on the second active regions 112.

A photoresist pattern 518 may be formed on the substrate having thefirst preliminary isolation regions 15 and the second isolation regions115.

The photoresist pattern 518 may expose a portion of the second region A2and a portion of the first region A1. A portion of the first hard masks6 a and a portion of the first preliminary isolation regions 15 may beexposed by the photoresist pattern 518. The photoresist pattern 518 mayhave the same shape and size as the photoresist pattern 318 describedabove with reference to FIGS. 24A and 25.

Referring to FIG. 35, an etching process using the photoresist pattern518 as an etching mask may be performed to form grooves 21 and a thirdtrench 133, identical to those described above with reference to FIG.26.

Referring to FIG. 36, after the photoresist pattern 518 is removed, asecond insulating material layer 23, covering the grooves 21 andconformally covering an inner wall of the third trench 133, may beformed in the same manner as that described above with reference to FIG.27.

Referring to FIG. 37, in the same manner as that described above withreference to FIG. 28, a third insulating material layer may be formed onthe substrate having the second insulating material layer 23, to fill aremaining portion of the third trench 133, and the third insulatingmaterial layer and the second insulating material layer (see 23 of FIG.36) may be planarized until the first and second hard masks 6 b and 106are exposed. In the first region A1, the second insulating materiallayer (see 23 of FIG. 36) may remain to be formed as a second portion 24of the first isolation region 27. The first preliminary isolation region15 remaining in the first region A1 may be referred to as a firstportion 15 of the first isolation region 27. In the second region A2,the second insulating material layer 23 (see FIG. 36) may remain to beformed as a first portion 124 of the third isolation region 136, and thethird insulating material layer may remain to be formed as a secondportion 134 of the third isolation region 136.

Then, after the process of etching back the first to third isolationregions 27, 115 and 136 in the same manner as that described withreference to FIG. 23 is performed, the transistor formation process maybe performed.

As set forth above, according to example embodiments, a first isolationregion may be formed between first active regions spaced apart from eachother by a first distance, and a second isolation region may be formedbetween second active regions spaced apart from each other by a seconddistance, shorter than the first distance. The first isolation regionand the second isolation region may commonly include a first insulatingmaterial, and the first isolation region may further include a secondinsulating material. The second insulating material may be a materialhaving relatively low thermal degeneration, as compared with that of thefirst insulating material. Thus, the second insulating material mayreduce thermal degeneration of the first isolation region, therebypreventing occurrence of defects such as cracks or the like in the firstactive regions.

As used herein, the term “and/or” includes any and all combinations ofone or m ore of the associated listed items. Expressions such as “atleast one of,” when preceding a list of elements, modify the entire listof elements and do not modify the individual elements of the list. Whileexample embodiments have been shown and described above, it will beapparent to those skilled in the art that modifications and variationscould be made without departing from the scope of the present inventiveconcept as defined by the appended claims.

What is claimed is:
 1. A semiconductor device comprising: first activeregions immediately adjacent to each other in a first horizontaldirection; second active regions immediately adjacent to each other inthe first horizontal direct; a first isolation region between the firstactive regions; and a second isolation region between the second activeregions, wherein the first isolation region comprises a first portioncomprising a first insulating material, and a second portion comprisinga second insulating material having characteristics different from thoseof the first insulating material, wherein the second portion has sidesurfaces opposing each other, wherein the side surfaces of the secondportion contact the first portion, wherein each of the first and secondactive regions has a linear shape extending in a second horizontaldirection perpendicular to the first horizontal direction, wherein awidth in the first horizontal direction of the first isolation region isgreater than a width in the first horizontal direction of the secondisolation region, and wherein a center region between an upper regionand a lower region of the second isolation region comprises the firstinsulating material.
 2. The semiconductor device of claim 1, wherein thesecond insulating material is harder than the first insulating material,the second insulating material is denser than the first insulatingmaterial, and/or the second insulating material has a second oxideetchant etching rate lower than a first oxide etchant etching rate ofthe first insulating material.
 3. The semiconductor device of claim 1,wherein a width in the first horizontal direction of the second portionis greater than a width in the first horizontal direction of the secondisolation region.
 4. The semiconductor device of claim 1, wherein thefirst portion contacts a bottom surface of the second portion.
 5. Thesemiconductor device of claim 1, wherein a length in a verticaldirection of the first portion is different from a length in thevertical direction of the second portion, and wherein the verticaldirection is perpendicular to the first horizontal direction.
 6. Thesemiconductor device of claim 1, wherein a length in a verticaldirection of the first portion is greater than a length in the verticaldirection of the second portion, and wherein the vertical direction isperpendicular to the first horizontal direction.
 7. The semiconductordevice of claim 1, further comprising: a first buffer oxide layerbetween the first isolation region and the first active regions; and asecond buffer oxide layer between the second isolation region and thesecond active regions.
 8. The semiconductor device of claim 7, whereinthe first buffer oxide layer and the second buffer oxide layer bothcomprise a thermal oxide.
 9. The semiconductor device of claim 7,wherein thicknesses of each of the first buffer oxide layer and thesecond buffer oxide layer is less than the width of the first isolationregion.
 10. The semiconductor device of claim 1, further comprising: afirst source/drain region on one of the first active regions; a secondsource/drain region on one of the second active regions; a first contactplug on the first source/drain region; and a second contact plug on thesecond source/drain region, wherein the second isolation region has alinear shape extending in the second horizontal direction, and whereinthe second source/drain region overlaps the second isolation region. 11.The semiconductor device of claim 10, wherein a width in the firsthorizontal direction of the first source/drain region is greater than awidth in the first horizontal direction of the one of the first activeregions, and wherein a width in the first horizontal direction of thesecond source/drain region is greater than a width in the firsthorizontal direction of the one of the second active regions.
 12. Thesemiconductor device of claim 10, wherein a width in the firsthorizontal direction of the second source/drain region is greater than awidth in the first horizontal direction of the first source/drainregion.
 13. A semiconductor device comprising: first isolation regionsimmediately adjacent to each other in a first horizontal direction;second isolation regions immediately adjacent to each other in the firsthorizontal direction; a first active region between the first isolationregions; a second active region between the second isolation regions; anactive base region; and third isolation regions, wherein the secondactive region and the second isolation regions are on the active baseregion, wherein the active base region, the second isolation regions andthe second active region are between the third isolation regions,wherein at least one of the first isolation regions comprises a firstportion comprising a first insulating material, and a second portioncomprising a second insulating material having characteristics differentfrom those of the first insulating material, wherein at least a part ofthe first portion is on side surfaces of the second portion, wherein afirst center region between a first upper region and a first lowerregion of the second isolation regions comprises the first insulatingmaterial, but not the second insulating material, wherein each of thefirst and second active regions has a linear shape extending in a secondhorizontal direction perpendicular to the first horizontal direction,and wherein a lower end of each of the second isolation regions is at ahigher level than a lower end of each of the third isolation regions.14. The semiconductor device of claim 13, wherein a width in the firsthorizontal direction of the at least one of the first isolation regionsis greater than a width in the first horizontal direction of at leastone of the second isolation regions.
 15. The semiconductor device ofclaim 13, wherein a width in first horizontal direction of at least oneof the third isolation regions is greater than the width in the firsthorizontal direction of at least one of the first isolation regions. 16.The semiconductor device of claim 13, wherein a length in a verticaldirection of at least one of the third isolation regions is greater thana length in the vertical direction of the at least one of the firstisolation regions.
 17. The semiconductor device of claim 13, wherein asecond center region between a second upper region and a second lowerregion of each of the third isolation regions comprises a thirdinsulating material having etch selectivity with respect to the firstinsulating material.
 18. A semiconductor device comprising: first activeregions on a substrate; first source/drain regions on the first activeregions; second active regions on the substrate; second source/drainregions on the second active regions; a first isolation region betweenthe first active regions; a second isolation region between the secondactive regions; first contact plugs on the first source/drain regions;and a second contact plug on the second source/drain regions, whereinthe first isolation region and the second isolation region each comprisea first insulating material, wherein the first isolation region furthercomprises a second insulating material different from the firstinsulating material, wherein the first isolation region comprises afirst portion comprising the first insulating material and a secondportion comprising the second insulating material, wherein at least apart of the first portion is on side surfaces of the second portion,wherein a center region between an upper region and a lower region ofthe second isolation region comprises the first insulating material,wherein the first active regions are adjacent to each other in a firsthorizontal direction, wherein the second active regions are adjacent toeach other in the first horizontal direction, and wherein each of thefirst and second active regions has a linear shape extending in a secondhorizontal direction perpendicular to the first horizontal direction.19. The semiconductor device of claim 18, wherein the first source/drainregions are spaced apart from each other, and wherein portions of thesecond source/drain regions are connected to each other.
 20. Thesemiconductor device of claim 18, further comprising: an active baseregion on the substrate; and third isolation regions on the substrate,wherein the second isolation region and the second active regions are onthe active base region, wherein the second isolation region, the secondactive regions, and the active base region are between the thirdisolation regions, wherein a width in first horizontal direction of thefirst isolation region is greater than a width in the first horizontaldirection of the second isolation region, wherein a width in the firsthorizontal direction of the third isolation region is greater than thewidth in the first horizontal direction of the first isolation region,wherein the second horizontal direction is perpendicular to the firsthorizontal direction, and wherein a lower end of the second isolationregions is at a higher level than a lower end of each of the thirdisolation regions.